The Unwanted Undead Adventurer Vol. 3 (manga)

After his evolution to a thrall, Rentt Faina sets out to explore an unmapped part of the Water Moon Dungeon. He finds a secret chamber, guarded by a mysterious woman. She offers him a treasure called the Map of Akasha as long as he keeps his silence about the secret chamber.

Rentt agrees, but before he can find out more about her, she teleports him out of the dungeon. Rather than fret and worry about this odd meeting, Rentt continues on his path to becoming a Mithril-class adventurer. His next hurdle? The Bronze-class Ascension Exam!His adventure as an undead is only just beginning!